U.S. patent number 9,677,005 [Application Number 14/260,378] was granted by the patent office on 2017-06-13 for integrated fuel processing with biomass oil.
This patent grant is currently assigned to Emerging Fuels Technology, Inc.. The grantee listed for this patent is Emerging Fuels Technology, Inc.. Invention is credited to Kenneth L. Agee, Mark A. Agee, Kym Brian Arcuri, Rafael Espinoza.
United States Patent |
9,677,005 |
Agee , et al. |
June 13, 2017 |
Integrated fuel processing with biomass oil
Abstract
A gas to liquids process with a reduced CO.sub.2 footprint to
convert both natural gas and a renewable feedstock material into
fuels or chemicals. In one embodiment of the invention, a natural
gas feed is converted into synthesis gas containing hydrogen and
carbon monoxide. A minor portion of the hydrogen is thereafter
extracted from the synthesis gas. The synthesis gas is converted to
hydrocarbons in a Fischer Tropsch reaction. The Fischer Tropsch
hydrocarbon product and a renewable feedstock are hydroprocessed
with the extracted hydrogen in order to produce fuels and/or
chemicals. Waste products from the renewable feed are recycled to
produce additional synthesis gas for the Fischer Tropsch
reaction.
Inventors: |
Agee; Kenneth L. (Tulsa,
OK), Agee; Mark A. (Tulsa, OK), Espinoza; Rafael
(Tulsa, OK), Arcuri; Kym Brian (Tulsa, OK) |
Applicant: |
Name |
City |
State |
Country |
Type |
Emerging Fuels Technology, Inc. |
Tulsa |
OK |
US |
|
|
Assignee: |
Emerging Fuels Technology, Inc.
(Tulsa, OK)
|
Family
ID: |
59011317 |
Appl.
No.: |
14/260,378 |
Filed: |
April 24, 2014 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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13529599 |
Jun 21, 2012 |
|
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|
61499545 |
Jun 21, 2011 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10G
3/54 (20130101); C10G 2/30 (20130101); C10G
47/24 (20130101); C10G 65/12 (20130101); C10G
1/002 (20130101); C10G 2/32 (20130101); C10G
3/50 (20130101); C10G 2/332 (20130101); Y02P
30/20 (20151101); C10G 2300/1011 (20130101) |
Current International
Class: |
C10G
2/00 (20060101); C10G 1/00 (20060101) |
Field of
Search: |
;585/254,303,240,241,242,250,252,257,275,300,310,314,330,379,440
;208/17,78 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Singh; Prem C
Assistant Examiner: Graham; Chantel
Attorney, Agent or Firm: Head, Johnson, Kachigian &
Wilkinson, PC
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of U.S. patent
application Ser. No. 13/529,599, filed Jun. 21, 2012, which claims
priority to U.S. Provisional Patent Application Ser. No.
61/499,545, filed Jun. 21, 2011, both of which are incorporated
herein by reference.
Claims
What is claimed is:
1. A reduced CO.sub.2 footprint gas and renewable feed to liquid
hydrocarbons and chemicals, combined process comprising the steps
of: a) converting natural gas to synthesis gas comprising H.sub.2
and CO; b) extracting a minor portion of the H.sub.2 of step a)
from the synthesis gas for downstream processing; c) converting the
ratio adjusted synthesis gas to hydrocarbons in a Fischer Tropsch
reaction; d) processing a renewable feed in a crushing plant to
extract a renewable oil feed, where the renewable feed and the
renewable oil feed are distinct from the natural gas, the synthesis
gas, and the Fischer Tropsch hydrocarbons; e) thereafter upgrading
the Fischer Tropsch hydrocarbons and the renewable oil feed with
the extracted hydrogen of step b) in a hydroprocessor in a GTL
plant to produce hydrocarbon products; f) recycling waste products
from the hydroprocessing back to step a), to make additional
synthesis gas; and g) using waste energy from step e) to supply at
least part of the energy required in the crushing plant to process
the renewable feed to extract the renewable oil in step d).
2. The process according to claim 1 wherein the renewable feed
stock material includes raw biomass feeds such as grasses, crops,
algae and seeds.
3. The process according to claim 1 wherein the hydrogen stream of
step b) is further purified to increase hydrogen purity.
4. The process according to claim 1 wherein synthesis gas is
produced in an autothermal reformer.
5. The process according to claim 1 wherein synthesis gas is
produced in a steam methane reformer.
6. The process according to claim 1 wherein the synthesized
hydrocarbon products and the renewable products may be blended
together in any ratio and may be blended together or separate with
other hydrocarbon products in any ratio.
7. The process according to claim 1 wherein the renewable oil is
processed in the same hydroprocessing unit and/or distillation unit
resulting in blended Fischer Tropsch and renewable products.
8. The process according to claim 1 wherein the renewable oil is
processed in separate hydroprocessing and distillation units
resulting in separate Fischer Tropsch and renewable products.
9. The process according to claim 1 wherein the hydrocarbon
products include jet, diesel or jet and diesel blend stocks,
synthetic crude, paraffin oils, paraffin waxes, base oils and
naphtha.
10. The process according to claim 1 wherein the Fischer Tropsch
reactor is a fixed bed, fluidized bed, ebulating bed, microchannel
or slurry bubble column reactor.
11. The process according to claim 1 wherein the catalyst utilized
in the Fischer Tropsch reaction is an iron based or cobalt based
catalyst.
12. The process according to claim 1 wherein any of the hydrocarbon
products may be subjected to additional hydroprocessing or
filtering processes to enhance color, stability or performance.
13. The process of claim 1 wherein step d) comprises crushing,
thermal depolymerization and pyrolysis.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process to co-process renewable
feedstock materials with a gas to liquids process wherein at least
a portion of hydrogen used to process the renewable materials is
produced in a gas to liquids process.
2. Prior Art
Mixtures of triglycerides and fatty acids can be hydroprocessed to
produce chemicals and fuels, such as jet and diesel fuel. Sources
of renewable feed can be seed oils, crop oils, animal fats,
recycled greases and oils including soy oil, jatropha, camalina,
palm oil, yellow grease, and other natural materials. The
processing of these materials requires a considerable volume of
hydrogen. By-products include CO.sub.2, water, propane and other
light hydrocarbons. These natural feed materials are generally
considered to be a renewable resource and are increasingly
desirable sources to produce fuels in a sustainable manner. The
production and use of fuels made from these resources also result
in a very low production of greenhouse gases.
Triglyceride feeds have been converted to fuels via a
transesterification reaction with methanol to make biodiesel for
many years. This process is becoming less desirable as it produces
a lower quality fuel. These same renewable feedstocks can be
converted to high quality fuels by processing with hydrogen over a
catalyst. This has been practiced as a standalone operation or by
co-processing in a conventional refinery.
The present invention provides a novel process to convert renewable
feed materials to fuels and chemicals by integrating operations
with a gas to liquids process.
A gas to liquids ("GTL") process integrates several process steps
to convert natural gas into fuels and/or chemicals.
First, natural gas is reacted with steam and/or oxygen to produce
synthesis gas comprising carbon monoxide and hydrogen. This is a
high temperature reaction involving a complex series of reforming
and combustion reactions. This step is typically catalytic and may
be performed in a steam methane reformer ("SMR") or an autothermal
reformer ("ATR"). This step can also be accomplished
non-catalytically in a partial oxidation reactor. As will be
described herein in detail, a preferred method of the present
invention is to use an ATR.
The synthesis gas produced in the first step is cooled and cleaned
before further use. This may also include adjusting the H.sub.2:CO
ratio to accommodate downstream requirements.
The second step in the GTL process is conversion of the synthesis
gas to hydrocarbon products. This is typically a Fischer Tropsch
reaction carried out over an iron based or cobalt based catalyst.
The reactor can take a number of forms, including a fixed bed,
fluidized bed, ebullating bed, microchannel or slurry bubble column
reactor. The catalyst and reactor must be carefully matched to
account for synthesis gas and product concentrations and heat
transfer limitations to operate at the desired performance.
The third step of the GTL process is to upgrade the raw hydrocarbon
products from the Fischer Tropsch reactor to produce one or more
products that meet a defined specification. For example, if a
middle distillate fuel is the desired product, it could be refined
to meet ASTM D-975 specifications.
The foregoing three key steps of the GTL process are integrated
with utilities such as oxygen production, power generation, water
treating, steam production and hydrogen management to meet the
objectives of a specific plant design. The GTL process also
requires additional infrastructure, such as safety systems, flares,
tanks, loading facilities to transport products and maintenance
facilities, etc.
An objective of the present invention is to use the GTL process to
leverage production of renewable products. This can be done with
any GTL process, but a preferred embodiment is to utilize small
modular GTL. Small, as used herein, is defined as between 500 to
5,000 barrels per day ("BPD"). The reason for this preference is
the relative size of typical renewable feedstock options. Renewable
materials are typically available in limited quantities at any
given location, for example, 500 to 1,000 BPD. For a small, modular
GTL plant, this is a good fit and the co-processing of the
renewable feed can be advantageous to the GTL plant. For large
50,000 to 100,000 BPD plants, the relatively small volumes of
renewable materials are too small to make a significant
contribution to the plant production.
There is currently a good deal of interest in production of
renewable fuels. One method of producing renewable fuels is to
gasify a raw renewable carbonaceous material to produce synthesis
gas and use a Fischer Tropsch reaction to produce hydrocarbon
products for upgrading. The chemistry of this process is similar to
a GTL process, but the process is much more complex. In the case of
a renewable biomass feed, it is typically an irregular shaped solid
material that must be stored on site, fed by auger or screw into a
gasifier, which typically operates at lower pressure. The resulting
synthesis gas must then be compressed and can have a variety of
contaminants, such as sulfur and halogen compounds, minerals, tars,
particulates and ash, that must be removed to very low levels
required by the Fischer Tropsch catalyst. By comparison, natural
gas flows into a GTL plant under pressure. It has a well-defined
composition with relatively few contaminants and commercial proven
methods for cleanup. Commercial SMR's and ATR's have demonstrated
operation at intermediate pressure (20-40 bars), which is ideal for
Fischer Tropsch operation without further compression.
Another method to produce renewable fuels is to hydroprocess a
renewable fat or oil, such as crop oils, animal fats, algae oils or
a polymer such as recycled plastics. These materials can be
processed with hydrogen to reduce the oxygen content and/or
molecular weight, thus deriving a marketable hydrocarbon product.
One of the challenges for processing these materials is the
availability of hydrogen. Hydrogen is expensive to produce and
requires significant infrastructure.
The objective of the present invention is to utilize the
infrastructure and resources of a GTL process, preferably a small
modular GTL process to co-process renewable feedstocks to provide
an integrated fuel processing system. Four key elements of the
integrated process result in improved efficiency and economics: 1.
Hydrogen from the GTL process--a typical SMR produces a synthesis
gas with a H.sub.2:CO ratio of 3:1. A typical ATR produces a ratio
of 2.2 to 2.6:1. Methane as a feedstock has a very high H.sub.2:CO
ratio (2:1) compared to a biomass feed, which is typically closer
to 1:1. Therefore, the synthesis gas obtained by conversion of
natural gas by the best available technology and the highest
efficiency possible will typically have excess H.sub.2 greater than
the 2:1 ratio required by the Fischer Tropsch reaction. This
hydrogen can be removed and purified for downstream processing,
such as upgrading Fischer Tropsch products and co-processing of
renewable products. 2. GTL infrastructure--a GTL plant will have a
significant amount of utilities and infrastructure that can be
leveraged for co-processing a renewable feed. If the renewable feed
is processed in a standalone plant, significant infrastructure
would be required. Most of this infrastructure is already in place
with a GTL plant with few additions required for the incremental
co-processing load. 3. Light product gas
utilization--hydroprocessing of the renewable feed results in loss
of product as the glycerides are decomposed into CO, CO.sub.2,
H.sub.2O and light hydrocarbons. In a standalone plant producing
fuels from these feeds, the light gas products cannot be recycled.
Some of the light gases can be collected as liquefied petroleum gas
("LPG"), but it has lower value. In the integrated process of the
present invention, these light gas products, which can be as much
as 15% of the feed, can be recycled to the reformer for production
of synthesis gas which can then be converted to liquid products.
This renewable material now becomes part of the Fischer Tropsch
product. 4. Reduced CO.sub.2 footprint--the integrated process of
the present invention results in a reduced level of CO.sub.2 added
to the atmosphere for the volume of products produced. By recycling
waste products from the hydroprocessing of the renewable feed, a
portion of the synthesis gas, and hence a portion of the Fischer
Tropsch products, are based on carbon from the renewable source.
While the Fischer Tropsch products are predominately made from
natural gas, the renewable content could be as high as 40% when
using a SMR to generate the synthesis gas. The Fischer Tropsch and
renewable products both require further processing with hydrogen to
make finished products.
The upgrading of these products can be done together or separate.
The Fischer Tropsch products to be upgraded typically include
paraffin hydrocarbons from C5 to C100. The long chain products C21+
can be hydrocracked to middle distillate fuels or can be
hydroprocessed to make solvents, waxes or lube base oils. For waxes
and base oils, it is desirable to minimize cracking, in which case
the heavy Fischer Tropsch products will be upgraded separately. If
the target is middle distillate fuels, the heavy Fischer Tropsch
waxy products (C21+) may be co-processed with the renewable feed.
In either case, the hydroprocessed product can be blended and
distilled or kept separate and distilled into finished products.
The final product upgrading configuration is defined by the product
target specifications. The finished products, whether derived from
natural gas or renewable feed, will be totally compatible and can
be blended in any proportion with each other or with other
petroleum derived products. Products that are co-processed may
result in renewable content of from 1% to 80%. When the renewable
products are processed separately, the renewable content of those
products is 100%. However, the separately processed GTL products
will still have a small renewable content of 1% to 40% due to
utilization of the light gases, which are not part of the desired
product slate, from the renewable materials that are recycled to
make additional synthesis gas.
The broad range of potential renewable content in the products is
based on the range of excess hydrogen available, depending on the
configuration of the reforming section of the GTL plant and the
ratio of renewable feedstock to Fischer Tropsch derived
hydrocarbons available for hydroprocessing. A SMR can be operated
efficiently to produce synthesis gas in an approximately 3:1
H.sub.2:CO ratio. The Fischer Tropsch reaction requires synthesis
gas in approximately 2:1 ratio. Therefore, in the case of a SMR,
there is substantial potential for excess hydrogen. This excess
hydrogen is typically recycled and used as fuel in the SMR, but
could be used for downstream hydroprocessing, resulting in a
substantial volume of hydrogen available for hydroprocessing. In
this case, the amount of renewable feed could result in
approximately three times as much renewable product as Fischer
Tropsch product. Theoretically, the SMR synthesis gas could be
shifted to all hydrogen and then the synthesis gas plant would be
strictly a hydrogen source that could process 100% renewable feed.
That configuration is not part of the scope of the present
invention.
The objective of the present invention is to efficiently utilize a
GTL plant to leverage additional production of renewable
feedstocks. The advantage to the GTL plant is to reduce the
CO.sub.2 footprint of the plant and utilize the infrastructure and
hydrogen of the plant to produce additional products. This includes
leveraging the light gas products from hydrodeoxygenating a
renewable feed to produce additional synthesis gas for the Fischer
Tropsch reaction, such products also being of a renewable nature.
In the case of an ATR, the amount of excess hydrogen is much less,
resulting in a renewable feed limit approximately equal to the
Fischer Tropsch production. The renewable feed could also be less,
depending on availability, hence the broad range. With the SMR
being the practical limit of the present invention for excess
hydrogen available for downstream processing and assuming the
renewable feedstock is not limiting, the maximum renewable content
of a blended product is approximately 80%. If the products are
hydroprocessed separately, the Fischer Tropsch derived products
could have approximately 40% renewable content due to recycling of
light gas components.
Co-processing of the renewable feeds has been proposed by Mackay et
al. (U.S. Patent Publication No. 2011/0113676). In this reference,
municipal solid waste ("MSW") is the primary feed. The MSW is
refined to produce a refuse derived fuel ("RDF") that is depleted
of inorganics. The RDF is gasified to make synthesis gas. The
synthesis gas is converted to a Fischer Tropsch raw product. Excess
hydrogen is used to upgrade a combined Fischer Tropsch product and
a triglyceride feed.
The present invention differs from the Mackay reference in that it
is based on reforming natural gas. Natural gas by nature has a high
hydrogen to carbon ratio. The result is that efficiently reforming
the gas provides a H.sub.2:CO ratio greater than required by the
Fischer Tropsch reaction. The excess hydrogen can efficiently be
utilized for downstream processing without sacrificing efficiency
in the GTL portion of the plant. In the case of MSW, as with most
biomass resources, the nature of the feed is deficient in hydrogen.
Therefore, the gasifier is operated with excess water in the feed
to produce a higher H.sub.2:CO ratio. While there may be
operational advantages to the high water feed, it is not optimum
from a carbon standpoint, as more CO.sub.2 will be produced in
order to make hydrogen not only for the renewable section of the
plant, but also to close the gap between the low H.sub.2 content in
the MSW to the ratio of about 2:1 needed for the Fischer Tropsch
process. Also, while the hydrogen derived from natural gas is not
renewable, it is much easier to produce since the contaminant level
in natural gas is significantly less than MSW. In the case of
natural gas reforming, the reformer can operate at 20-40 bars,
sufficient to pass directly to the Fischer Tropsch reactor without
further compression. Processing MSW at these pressures is costly
and inefficient.
The Mackay process does not take advantage of recycling waste
products from hydroprocessing of renewable feeds. The Mackay
process also does not find advantage to the reduced CO.sub.2
footprint enjoyed by the present invention, as the nature of the
Mackay primary feed is considered to be renewable.
A type of co-processing of renewable feeds is taught by Knuuttila
(U.S. Patent Publication No. 2010/0317903). In this reference, a
biological feed is gasified to make synthesis gas. The synthesis
gas is converted to Fischer Tropsch hydrocarbon products. The
Fischer Tropsch hydrocarbon product is hydroprocessed and a
separate bio oil is also hydroprocessed. The Fischer Tropsch
products and hydroprocessed bio oils are combined and
fractionated.
The present invention differs from the Knuuttila reference in that
synthesis gas is generated by reforming natural gas, whereas
Knuuttila gasifies biomass. In the present invention, excess
hydrogen is efficiently extracted from the synthesis gas for
downstream hydroprocessing, whereas Knuuttila produces hydrogen in
a separate reformer by reforming waste components or imported
methanol, recognizing that the biomass feed stream is deficient in
hydrogen. The Knuuttila design gains no advantage of reduced carbon
footprint enjoyed by the present invention, as it utilizes
biological feed.
Gasification of a carbonaceous feed is taught by Blevins et al.
(U.S. Patent Publication No. 2011/0178185). While the carbonaceous
feed is clearly directed at renewable biomass, natural gas is
included in the definition of carbonaceous feed. Unlike the present
invention, this reference does not teach efficient extraction of
hydrogen for downstream processing of renewable feeds or
co-processing of such streams.
The present invention is directed to a process to efficiently
utilize resources, such as hydrogen and infrastructure of a gas to
liquids process, to efficiently co-process renewable fats and oils
or polymers. Such processing enhances the GTL operation by reducing
the carbon footprint, adding a small amount of renewable material
into the Fischer Tropsch product and adding a new renewable product
in a very capital and energy efficient manner.
A purpose and object of the present invention is to provide an
integrated fuel processing system which has advantages over either
a natural gas to liquids process or a biomass hydroprocessing
process.
SUMMARY OF THE INVENTION
Renewable feedstocks containing triglycerides and free fatty acids
can be advantageously converted into fuels and chemicals in
combination with a gas to liquids (GTL) process. Excess hydrogen
and export energy in the form of steam and/or fuel gas from the GTL
process can be used to produce and hydroprocess the renewable
feedstock.
A known gas to liquids process has three main components: 1)
Conversion of natural gas to syngas (H.sub.2+CO); 2) Conversion of
syngas to hydrocarbons; and 3) Hydroprocessing of the synthesized
hydrocarbons to make finished products.
The preferred method of the present invention is to use natural gas
as the feedstock; however, it is within the scope of the process to
use any carbonaceous feed. The syngas produced in the first step
provides a source of hydrogen for the third step. This hydrogen may
be removed by membrane or pressure swing adsorption ("PSA") or a
combination or any method known to one skilled in the art. Only a
fraction of the hydrogen is removed as required in the
hydroprocessing step and to adjust the H.sub.2:CO ratio for the
Fischer Tropsch synthesis.
In the process of the present invention, the renewable natural feed
material can be co-processed with the synthesized oil. The
processing may be in one reactor, such as a hydrocracker, or in
separate reactors, depending on whether it is desirable to end up
with mixed products or separate products. It may also be desirable
to process the renewable feed separate from the Fischer Tropsch
derived feed, as the Fischer Tropsch material is much heavier
(except when the renewable feed is a polymer) and will require more
hydrocracking if, for example, the desired product is a middle
distillate fuel. If the renewable products are hydroprocessed
separate from the synthesized products, the finished products may
be blended or used separately and both may be blended together or
separately with conventional crude oil derived products.
In all cases, a portion of the hydrogen produced in the first step
of the GTL process is used to hydroprocess the GTL product and the
renewable oil, and export energy from the GTL process is used to
process a renewable feed (crush or thermally depolymerize, for
example) to produce all or part of the renewable oil.
Hydroprocessing of renewable oils in this manner results in the
production of by-products, such as H.sub.2O, CO, CO.sub.2, propane
and other light hydrocarbon by-products. All or a portion of these
by-products can be advantageously recycled back to the first step
of the GTL process to produce more synthesis gas, thereby
increasing both the carbon and energy efficiency of the entire
process.
When the synthesized products are co-processed or blended with the
renewable products, the result is a unique composition of matter
containing a blend of natural gas derived and renewable molecules.
Products synthesized by the Fischer Tropsch reaction have a very
uniform distribution of highly paraffinic molecules, including even
and odd carbon numbers. The hydrocarbon chains produced by Fischer
Tropsch include very long waxy chains. When they are hydrocracked
to produce a jet or diesel fuel, the resulting product is distilled
to the range required for the fuel. A diesel fuel, for example, has
a carbon distribution with hydrocarbon chains ranging from about
C10-C19. The hydrocracked material has paraffin and isoparaffin
molecules in this range.
When the feedstock is a triglyceride and/or fatty acid, the
naturally occurring products have a narrow distribution of carbon
number. Triglycerides have three fatty acid chains linked to a
three carbon backbone with an oxygen molecule between each chain.
The three side chains are even number carbon chains with a narrow
distribution of chain length generally in the C16-C20 range with a
significant distribution around C18, which is acceptable for
diesel, but outside the range of commercial jet fuel.
Decarboxylation of the side chains will produce a fraction of odd
number carbon chains.
When hydroprocessed, the oxygen molecules and the three carbon
backbone of the triglyceride produce by-products including
H.sub.2O, CO, CO.sub.2, propane and other light hydrocarbons. As
such, this represents loss of material from the feed that will not
be in the final product. Also, the C18 paraffin product can be used
in the diesel product, however, commercial diesel typically
contains a distribution of hydrocarbons in the C9 to C20 range. The
diesel product can be improved with additional cracking and
isomerization of the C18 to get a full range diesel with improved
cold flow properties. This cracking will result in production of
some shorter chain material that is too light for diesel or jet
and, therefore, results in production of lower value (C5-C9)
naphtha. However, these lighter products can also be recycled back
to the reformer and converted to synthesis gas for further
conversion to more desirable products.
When blended or co-processed with the synthesized material and/or
petroleum derived products which have a full boiling range, there
is less need to crack the renewable material.
Therefore, it can be advantageously processed to reduce the amount
of light cracked material. Also, any light cracked material that is
produced can be recycled to the first step to produce syngas that
will be converted to product by Fischer Tropsch synthesis. The
Fischer Tropsch synthetic material may therefore be composed of
natural gas derived and renewable derived components.
The integrated process, if co-processed or blended, will result in
a unique product composition. In the case of a diesel product, for
example, the highly predictable distribution from a Fischer Tropsch
synthesis and hydrocracking will be modified, showing a spike in
the C16-C18 carbon number range from the addition of the renewable
feedstock. The products will also show measurable amounts of C14
from the renewable materials.
The co-processing and/or blending of the renewable product with a
GTL process can be done at great advantage to get the maximum
benefit of low cost hydrogen and efficient utilization of the
renewable feedstock. This process efficiently utilizes the
resources (hydrogen) and infrastructure of the GTL process. It also
efficiently utilizes lower value by-products of the co-processed
renewable feed, such as propane, by producing additional synthesis
product resulting in a reduced CO.sub.2 footprint.
There are further benefits that may be realized by the present
invention. Additional benefit to the co-processing facility may be
derived by adding a processing facility (crushing, pyrolysis,
thermal depolymerization, etc.) to produce the renewable oil feed,
such as crushing canola seed, for example. The seed can be
mechanically crushed, producing an oil and a meal product. The meal
can be further processed, if desired, to extract more of the oil.
Such processing typically involves solvent extraction. The crushing
facility requires infrastructure, such as buildings and utilities
and energy to operate. Integration of a crushing plant into the
design of the present invention could be beneficial to the overall
operation. The integrated GTL and renewable processing facility of
the present invention will have operations capabilities that will
be required by the crushing plant such as: operations personnel,
roads, office buildings, laboratory, maintenance buildings, tankage
and safety equipment. The GTL plant will produce export energy in
the form of steam and/or fuel gas which can be used by the crushing
plant. The meal produced can be sold into the animal feed market to
reduce the net cost of the oil that can be processed with the GTL
derived oil.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a process flow diagram of a first preferred embodiment of
integrated fuel processing with biomass oil as set forth in the
present invention.
FIG. 2 is a process flow diagram of a second preferred embodiment
of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The embodiments discussed herein are merely illustrative of
specific manners in which to make and use the invention and are not
to be interpreted as limiting the scope of the present
invention.
While the invention has been described with a certain degree of
particularity, it is to be noted that many modifications may be
made in the details of the invention's construction and the
arrangement of its components without departing from the spirit and
scope of this disclosure. It is understood that the invention is
not limited to the embodiments set forth herein for purposes of
exemplification.
FIG. 1 is a schematic diagram of a first preferred embodiment of
the invention. In FIG. 1, natural gas and steam 1 are fed with
oxygen 2 to a reformer 16. The reformer 16 is preferably a high
temperature autothermal reformer (ATR). The preferred syngas
generation technology is an ATR, however, if the renewable oil (to
be described herein) requires more hydrogen than can be produced by
the ATR, the syngas generation method could be a steam methane
reformer, for example, which requires more steam and no oxygen.
Synthesis gas 3, comprising carbon monoxide and hydrogen, exits the
reformer 16. The synthesis gas typically has an H.sub.2:CO ratio of
2.2 to 2.6. The synthesis gas stream is separated into a hydrogen
rich stream and a ratio adjusted synthesis gas stream in a hydrogen
membrane separation unit 17. Such hydrogen rich stream may be
further purified with PSA, for example. The ratio adjusted
synthesis gas stream 4 has a preferred ratio of about 2:1. This
ratio may be further adjusted within a Fischer Tropsch reactor unit
18, depending on the reactor configuration and operating
conditions.
The ratio adjusted stream 4 is directed to a Fischer Tropsch
reactor unit 18. The Fischer Tropsch unit 18 contains one or more
Fischer Tropsch reactors configured in parallel and/or series with
or without recycle to achieve desired targets for conversion and
selectivity. The reactors may be fixed bed, fluidized bed,
ebullating bed, microchannel or slurry bubble column reactors. Any
reactor known to one skilled in the art may be used. The reactors
may be configured in a manner desirable to achieve the objective of
converting synthesis gas to hydrocarbon products. The H.sub.2:CO
ratio may be adjusted within the Fischer Tropsch unit to enhance
performance, such as hydrocarbon selectivity.
Products from the Fischer Tropsch reactor may be separated a number
of different ways. FIG. 1 illustrates three product streams: 1) a
light gaseous stream 6 which contains unreacted synthesis gas
H.sub.2, CO, CO.sub.2, any inerts that entered in feed streams and
light hydrocarbons, primarily C1-C4; 2) an intermediate liquid
hydrocarbon stream 7, predominately C5-C20 hydrocarbons. This
stream is very paraffinic, but may contain significant amounts of
olefins and alcohols. The concentration and distribution of
non-paraffinic hydrocarbons may vary significantly depending on the
catalyst and operating conditions employed in the Fischer Tropsch
reactors; and 3) a heavy hydrocarbon stream 8 containing
predominately C21+ paraffinic hydrocarbons.
All or a portion of the intermediate liquid hydrocarbon stream 7
may be blended with the heavy hydrocarbon stream 8 and a renewable
feed stream 9 for hydroprocessing in unit 19, which includes
hydrocracking, hydrodeoxygenation and hydrodecarboxylation. A
crushing plant 21 may optionally utilize facilities, infrastructure
and energy from the GTL plant to produce the renewable feed 9.
Optionally, an external source of renewable oil can be added to
stream 9.
Intermediate hydrocarbon stream 7 can completely by-pass the
hydroprocessing unit or can be hydroprocessed in its entirety or
any portion thereof. The amount that will be hydroprocessed will
depend on the ratio of stream 7 to stream 8 produced by the Fischer
Tropsch reactor and the specification of the finished product
desired.
As seen in FIG. 1, raw biomass feed 22 is mechanically crushed in a
crushing plant 21 to produce oil 9 and meal 23. Export energy from
the GTL plant in the form of fuel 13 and/or steam 24 may be used to
provide all or a part of the energy required to operate the
crushing plant 21. Optionally, all or a part of fuel stream 13
and/or steam stream 24 can be used to generate electrical power to
be used in the crushing plant 21 and/or in the chemical
processes.
High purity hydrogen 5, which has been separated from the synthesis
gas, is added to the hydroprocessing unit 19. This hydrogen may be
further purified by pressure swing adsorption, for example, before
addition to hydroprocessing unit 19. A portion of the intermediate
liquid stream 7 may be by-passed around hydroprocessing unit 19 to
provide a small amount of primary alcohols as a lubricity improver
in the finished product(s) 15.
The hydroprocessed product 10 is fed to a distillation unit 20 for
separation. Purge gases 26 from hydroprocessing are added to stream
11 for recycle to the reformer 16 or used as fuel gas. Purge gas 26
may optionally be recycled to the hydrogen membrane separation unit
17 to remove hydrogen.
The light gaseous stream 11 exiting the distillation unit 20
contains light hydrocarbons, primarily C1-C4, which can
advantageously be recycled to reformer 16 by adding them into the
reformer feed, resulting in a portion of the synthesis gas going to
the Fischer Tropsch synthesis being of renewable origin.
A light paraffinic naphtha stream 14 is produced and then removed
from the top of the distillation column 20. A middle distillate
product 15 is produced and then removed from the side of the
distillation column 20. The distillate product may be SPK
(synthetic paraffinic kerosene for jet fuel), diesel, solvents or
distillate blend stock. A heavy bottom cut 12 that is heavier than
the desired end point of the middle distillate product is produced
and then removed from the bottom of the distillation column and
recycled to the hydroprocessing unit 19. This product will
thereafter be cracked to extinction.
The distillate product may preferably be a jet fuel (SPK) or diesel
product. If the distillate product requires a low pour point, it
may be necessary to further hydrotreat and hydroisomerize one or
more of the feed steams to increase the isoparaffin content of the
products beyond what is produced by hydrocracking. All or a part of
the straight run Fischer Tropsch liquid, for example, in the C9-C20
range, can be fed into a hydrotreater and subsequently into a
hydroisomerization reactor. This additional hydroprocessing
improves the pour point of the final product, allowing attainment
of jet fuel (SPK) specifications. One skilled in the art can make
such adjustments, depending on the product slate and target
specifications.
FIG. 2 is an alternate preferred embodiment of the present
invention. In the process illustrated in FIG. 2, natural gas and
steam 1 is fed along with oxygen 2 to a reformer 19. The reformer
is preferably an autothermal reformer (ATR). The preferred syngas
generation technology is an ATR, however, if the renewable oil
requires more hydrogen than can be produced by the ATR, the syngas
generation method could be a steam methane reformer, for example,
which requires more steam and no oxygen.
A synthesis gas stream 3, comprising carbon monoxide and hydrogen,
is produced and thereafter exits the reformer 19. The synthesis gas
stream typically has a H.sub.2:CO ratio of 2.2 to 2.6. The
synthesis gas stream is separated into a hydrogen rich stream and a
ratio adjusted synthesis gas stream in a hydrogen membrane
separation unit 20. The hydrogen rich stream may be further
processed by PSA, for example, to enrich the hydrogen
concentration. The ratio adjusted synthesis gas stream 4 has a
preferred ratio of about 2:1. This ratio may be further adjusted
within a Fischer Tropsch unit 21, depending on the reactor
configuration.
The Fischer Tropsch unit 21 contains one or more Fischer Tropsch
reactors configured in parallel and/or series with or without
recycle to achieve the desired targets for conversion and
selectivity. The reactors may be fixed bed, fluidized bed,
ebullating bed, microchannel or slurry bubble column reactors. Any
reactor known to one skilled in the art may be used. The reactors
may be configured in a manner desirable to achieve the objective of
converting synthesis gas to hydrocarbon products. The H.sub.2:CO
ratio may be adjusted within the Fischer Tropsch unit to enhance
performance, such as hydrocarbon selectivity.
Products produced in and exiting from the Fischer Tropsch reactor
may be separated a number of different ways. FIG. 2 illustrates
three product streams: 1) a light gaseous stream 17 which contains
unreacted synthesis gas H.sub.2, CO, CO.sub.2, any inerts that
entered in feed streams and light hydrocarbons, primarily C1-C4; 2)
an intermediate liquid hydrocarbon stream 8, predominately C5-C20
hydrocarbons. This stream is very paraffinic, but may contain
substantial amounts of olefins and alcohols. The concentration and
distribution of non-paraffinic hydrocarbons may vary significantly
depending on the catalyst and operating conditions employed in the
Fischer Tropsch reactors; and 3) a heavy hydrocarbon stream 8a
containing predominately C21+ paraffinic hydrocarbons.
The intermediate liquid hydrocarbon stream 8 and heavy hydrocarbon
stream 8a can be processed together or separately in a
hydroprocessing unit 22, depending on desired target product
specifications. If paraffinic solvents 14 and waxes 11 are the
target products, the hydroprocessing is a simple hydrotreating
reaction used to saturate olefins. After distillation, there may be
need to polish one or more of the streams to improve color. If the
objective is to make base oils 10 in hydroprocessing unit 22, the
operation will include a hydroisomerization reactor to increase the
isoparaffin content of the feed stream. Again, it may be necessary
to polish one or more finished products to improve color. Light
hydrocarbons 16 generated by mild cracking in hydroprocessing unit
22 may be recycled to reformer 19 for producing additional
synthesis gas or may be used as fuel gas 18. The hydrogen rich
stream 5 extracted by membrane unit 20 can be purified (i.e. such
as by pressure swing adsorption) and split into two streams, stream
6 and 7. Stream 6 provides hydrogen for hydroprocessing unit 22 and
stream 7 provides hydrogen necessary for hydroprocessing in
hydroprocessing unit 23 with renewable feed stream 12, which
optionally includes renewable feed 28 from an external source.
Intermediate hydrocarbon stream 8 can by-pass the hydroprocessing
unit and be added back before distillation (not shown) or can be
hydroprocessed in its entirety or any portion thereof. The amount
that will be hydroprocessed will depend on the ratio of stream 8 to
stream 8a produced by the Fischer Tropsch reactor and the
specification of the finished product desired.
A crushing plant 24 may optionally utilize facilities,
infrastructure and energy from the GTL plant to produce a renewable
feed oil 12. The plant 24 could optionally be any type of plant
that removes a renewable oil from a renewable feed, such as
crushing, thermal depolymerization and pyrolysis. Raw biomass feed
25 is at least mechanically crushed in this example to produce oil
12 and meal 27. Export energy derived from the GTL process
described herein in the form of fuel 18 and/or steam 26 may be used
to provide all or a part of the energy required to operate the
crushing plant 24. Optionally, all or a part of fuel stream 18
and/or steam stream 26 can be used to generate electrical power to
be used in the crushing plant and/or in the chemical processes. The
renewable feed will be hydrodeoxygenated and/or hydrodecarboxylated
in hydroprocessing unit 23, resulting in production of H.sub.2O,
CO, CO.sub.2. These by-products, along with light hydrocarbon gases
from hydrocracking stream 15, can be recycled to the reformer 19 to
produce additional synthesis gas. The hydrocarbon products can be
saturated and used as paraffin solvents 14 or subjected to
additional hydroisomerization, if required, in hydroprocessing unit
23 to produce jet (SPK) and diesel fuels 13.
The products from hydroprocessing unit 22 and hydroprocessing unit
23 may be blended or kept separate. The products are compatible
with petroleum derived products and may be blended with them in any
proportion.
In this configuration, the products from hydroprocessing unit 23
are totally renewable, while the products from hydroprocessing unit
22 are only partially renewable.
A non-limiting example utilizing the process set forth in FIG. 1 is
illustrative of the process of the present invention.
Example
Natural gas (21.6 MMSCFD) was directed to and reacted in an
autothermal reformer along with (13.1 MMSCFD) 99.5% oxygen to
produce 73.2 MMSCFD of synthesis gas 3 of the following
composition:
TABLE-US-00001 Component Mol % H.sub.2 64.98 CO 28.14 CO.sub.2 5.54
Ar .08 N.sub.2 .18 C.sub.1 1.08
A hydrogen membrane separation unit 5 was used to extract
approximately 4.0 MMSCFD of a hydrogen rich stream from the
synthesis gas stream. The hydrogen was further purified and
compressed for later use in the product refining section of the
process.
The adjusted ratio synthesis gas, after hydrogen extraction, was
reacted over a cobalt Fischer Tropsch catalyst in a Fischer Tropsch
reactor in multiple stages to a CO conversion of approximately 92%,
resulting in the production of 2,218 BPD of a synthetic crude
product. The synthetic crude is collected in separators as a heavy
Fischer Tropsch liquid (wax 1,748 BPD) and a light Fischer Tropsch
liquid (oil 471 BPD).
Approximately 850 tons/day of canola seed is mechanically crushed
producing 1,900 BPD of refined canola oil and 592 tons/day of a
high quality canola meal. Export energy from the process, in the
form of steam, is used to heat the canola seeds to 200.degree. F.
to enhance the crushing operation. Medium pressure steam from the
GTL process is also used to drive the mechanical crushing unit,
which requires 2,400 HP. The GTL tail gas or steam could also be
used to generate power to operate the crushing plant. Approximately
10 MMBTU/HR of medium pressure steam is required to heat the
biomass to the desired temperature. The cost to provide the
renewable oil on site is greatly reduced by utilizing energy
resources and infrastructure of the GTL plant and selling the meal
to partially offset the oil cost.
The heavy Fischer Tropsch syncrude (1,748 BPD) is blended with a
portion of the light syncrude and approximately 1,900 BPD of clean
degummed canola oil. This combined mixture is sent to the
hydroprocessing section of the plant where sequential reactors
fully hydrogenate the canola oil, producing linear paraffins along
with water, CO.sub.2 and light hydrocarbons (predominantly
propane). The combined product is fractionated so that the C19+
portion is sent to a hydrocracker to produce jet and diesel range
hydrocarbons with modest amounts of naphtha (C5-C9) and light
hydrocarbons C4-, which can be recycled back to the front of the
system to make additional syngas. The C19- fraction is sent to a
hydroisomerization unit to convert the linear paraffins to
isoparaffins. Some cracking can occur in this reactor, leading to
additional naphtha and C4- hydrocarbons, which are recycled to
produce additional syngas. The effluent hydrocarbon streams,
consisting of C5+ linear and branched isomers, are sent to a final
fractionation tower where the naphtha, jet and diesel products are
recovered. The amount of each product can vary, depending upon the
extent of hydroisomerization and hydrocracking that occurs in the
reactors. In this example, the product slate consists of 460 BPD of
naphtha, 2,330 BPD of jet (SPK) and 1,260 BPD of diesel. The diesel
product contains over 58% renewable carbon, while the jet contains
approximately 45% renewable carbon. The product slate and amount of
renewable carbon can vary, depending on the hydroprocessing
configuration. As more jet is produced, the diesel product volume
decreases and the naphtha volume increases.
Whereas, the present invention has been described in relation to
the drawings attached hereto, it should be understood that other
and further modifications, apart from those shown or suggested
herein, may be made within the spirit and scope of this
invention.
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